1. Field of the Invention
The present invention relates to a method and forceps for removing nuclear fragments of a lens during eye surgery.
2. Description of the Prior Art
In some people, especially the elderly, the condition of one or both eyes will deteriorate and the patient may develop cataracts in either or both eyes. The development of cataracts is a condition in which the lens of the eye becomes at least partially cloudy or even opaque. When this condition develops it is necessary to remove the internal portions of the natural lens of the eye in order to restore the patient's sight. The natural lens is usually replaced with a tiny artificial prosthetic plastic lens.
The exterior surface of the lens of the eye is termed the capsule. The capsule completely surrounds and encloses an inner lining of soft material termed the cortex. The cortex in turn encapsulated the nucleus of the lens therewithin. The nucleus of the lens is a relatively hard substance, as contrasted with the surrounding cortex. It is usually within the nucleus that cataracts develop and removal of the nucleus is essential to restoration of the patient's sight.
There are several methods of removal of the internal portions of the lens of an eye in performing cataract surgery. One method is to "express" the lens. In this method a relatively large incision is made in the capsule of the lens and the nucleus of the lens is forced out of the capsule by external pressure. The disadvantage of this technique is that the recuperation time is lengthy, typically about a month. During this period, the patient cannot exert any strain or lift objects of even moderate weight or complications are likely to develop.
Another technique for removal of the internal parts of the lens in cataract surgery is phaco emulsification. In this technique only a local anesthetic is used on the patient and phaco emulsification needle is inserted into the lens of the eye through a very small incision. The phaco emulsification needle is vibrated at ultrasonic frequency to break up the nucleus of the lens using ultrasound. The needle is hollow and suction is exerted through a central axial passageway of the needle, while fluid to carry the emulsified nuclear particles is injected into the capsule of the lens through an annular passageway that surrounds the hollow needle. By breaking up the lens nucleus ultrasonically and aspirating the nuclear particles in a flushing fluid the nucleus of the lens can be evacuated from the capsule. Preferably also the cortex of the lens is similarly evacuated from the capsule using an irrigation-aspiration tip. Because the incision is so tiny a patient can resume normal activities the following day after the successful performance of lens nucleus removal by phaco emulsification.
One recurring problem which has existed with phaco emulsification lens removal is that with the use of a rapidly vibrating, tiny sharp needle it is not uncommon for accidental incisions to be made in the wall of the capsule facing the vitreous humor of the eyeball. When this occurs vitreous humor from within the eyeball will well up into the capsule through the slit or tear in the capsule. Such accidental slits or incisions in the capsule wall are of no great consequence in themselves. However, not infrequently ultrasonically disintergrated fragments of the nucleus will migrate from the capsule through an incision or slit created during phaco emulsification and pass into the vitreous humor in the eyeball.
The presence of such nuclear fragments in the vitreous humor can create severe complications. Specifically, unlike particles of the cortex, nuclear fragments of the lens will not dissolve by themselves in the vitreous humor. To the contrary, they remain and cause inflammation and increased pressure within the eyeball. Therefore, it is very important for any nuclear fragments to be removed at once before they pass from the lens capsule deep into the vitreous humor. Once nuclear fragments descend into the vitreous humor in the enclosure of the sclera they become very difficult for the surgeon to locate. When this occurs the surgeon has no choice but to close up the eye. Subsequent, more complex surgery must then be performed at a later time by a vitriol-retinal surgeon, during which the patient must be given a general anesthetic.
The phaco emulsification needle should not be used for the continued removal of nuclear fragments of the lens from the lens capsule once vitreous humor has entered the capsule through a slit in the capsule wall. That is, the surgeon should not attempt to aspirate the nuclear fragments from the vitreous humor that has entered the capsule by bringing the aspirating tip of the needle to bear upon any such nuclear fragments in the vitreous humor. The vitreous humor is a soft, jelly-like sustance which tends to be somewhat cohesive. When suction is exerted through the phaco emulsification needle, force is transmitted through the substance of the vitreous humor to the interior walls of the sclera. Such forces which are transmitted through the vitreous humor can even cause detachment of the retina, which is a very serious complication to the surgery.
According to conventional acceptable techniques phaco emulsification must cease once a slit has been created in the side of the capsule facing the vitreous humor. The surgeon then attempts to remove any remaining nuclear fragments using a lens loop. A lens loop is an implement in which a tiny loop is formed in the end of a wire. The loop is inserted into the lens capsule and positioned beneath a nuclear fragment remaining in the capsule. The surgeon then attempts to drag the fragment free from the vitreous humor that has entered the capsule. Each fragment must be removed one by one. However, since the vitreous humor is so sticky, the nuclear fragments are very difficult to extract from the vitreous humor using a lens loop.